基于2D电液比例换向阀的压扭放大驱动作用机理研究

Due to the limited thrust of proportional electromagnet, conventional direct-acting electro-hydraulic proportional direction valve has limitations of small flow and pressure.Thus, the pilot electro-hydraulic proportional direction valve has to be applied in some situation of the large flow, however, the pilot valve has limitations of complex structure and can not work at a zero system pressure. In order to change this situation, a new electro-hydraulic proportional directional valve, which was composed of 2D directional valve (flow valve), compression torsion coupling and proportional electromagnet in a line, was proposed to enhance the working flow and pressure by a large margin. At the same time, the struction of the valve was simplified and it could also be realized at the zero system pressure as direct-acting electro-hydraulic proportional direction valve did. Therefore, this reasearch has not only the important engineering application value, but also the great theoretical value for the electro-hydraulic proportional direction valve technology. A casing bi-directional proportional electromagnet are designed. It is required that the size and the output force are small, but the output displacement is relatively large. The compression torsion coupling is used to realize motion conversion and amplify the thrust force of proportional electromagnet, therefore the unfavorable influence of friction force between spool and valve sleeve on proportional characteristics can be effectively overcome.

传统的直动式电液比例换向阀由于受比例电磁铁推力的制约，其流量和压力不能达到较高的水平，致使目前对一些大流量的应用场合都必须采用导控型电液比例换向阀，而导控型电液比例换向阀结构复杂，不能像直动式阀一样在零压情况下工作。为此，提出一种由比例电磁铁、压扭联轴器和2D换向阀三者共轴联结的新型电液比例换向阀，旨在显著提高电液比例换向阀控制流量，同时使其结构简化，在零压下也可以像直动式比例换向阀那样实现比例控制功能。设计一种套管式双向比例电磁铁，要求其尺寸和输出力较小，但输出位移相对较大。采用压扭放大驱动技术，旨在通过压扭联轴器将比例电磁铁的轴向推力转换为切向驱动力，并进行放大，从而有效地克服了阀芯和阀芯孔之间的摩擦力，消除非线性因素对阀的比例特性所造成的不利影响，提高了比例阀的性能。

利用一体式弹性压扭联轴器传递无摩擦和间隙的优点，将比例电磁铁直线输入位移转为阀芯旋转角度，阀芯两端压差驱动阀芯同时带动联轴器运动，由于联轴器轴向间隙恢复使阀芯角度反转致初始位置达到两端无压差，阀芯平衡静止。本项目通过Maxwell仿真分析比例电磁铁磁路，设计出一种行程大而推力较小的套管式电磁铁。为了研究磁路的非线性，采用分段的正弦曲线描述牵引力幅值与电流之间的关系，理论结果与试验结果具有较好的一致性。应用ANSYS软件分析一体式弹性压扭联轴器，根据其应力应变情况优化其结构。针对液压滑阀阀体沉割槽内液体流速不同会产生径向卡紧力的问题，利用CFD软件对沉割槽处阀芯台肩所受径向压力分布进行研究，建立了沉割槽处阀芯台肩上压力分布的数学模型，分析了沉割槽尺寸及流量对阀芯径向压力分布的影响。阀芯台肩上径向压力分布不均匀，且压力值随入口流量、沉割槽深度和宽度呈二次多项式函数关系上升；随压力点位置从远离出口位置至靠近出口呈平方关系下降；当阀口开度为0.5mm、流量为40L/min时阀芯台肩径向卡紧力为4.2N，是流量为10L/min情况下的16倍，且沉割槽深度减半后，卡紧力增至14.47N。最后，提出了一种偏心沉割槽结构，仿真结果表明，入口流量大于40L/min时，偏心沉割槽结构中径向压力分布的不均匀度比传统同心结构提高了64%以上，有效降低阀芯径向卡紧力。主阀零位导控级泄漏极小；在15MPa时，导控级泄漏为0.2L/min，主阀泄漏为8.5L/min；在27MPa时，流量为190L/min；当在开环控制下叠加一定颤振信号时，滞环小于4.5%，相位滞后90°对应的频宽为4Hz，阶跃响应的上升时间约为0.55s。本项目的研究成果将对液压阀应用于高精度控制系统提供理论方法，提供了一种直动导控一体式阀芯控制方法。